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Chemical Fact Sheet

Chemical Abstract Number (CAS #) 75058
CASRN 75-05-8
SynonymsAcetonitrile
Methyl cyanide
Ethanenitrile
Analytical Methods EPA Method 8260
Molecular FormulaC2H3N

Link to the National Library of Medicine's Hazardous Substances
Database for more details on this compound.

Use In organic synthesis as starting material for acetophenone, alpha-naphthaleneacetic acid, thiamine, acetamidine. To remove tars, phenols, & coloring matter from petroleum hydrocarbons which are not soluble in acetonitrile. To extract fatty acids from fish liver oils & other animals & vegetable oils. Can be used to recrystallize steroids. As an indifferent medium in physicochemical investigations. Wherever a polar solvent having a rather high dielectric constant is required. As medium for promoting reactions involving ionization. As a solvent in non-aqueous titrations. As a nonaqueous solvent for inorganic salts. Acrylic fibers; pharmaceuticals; perfumes; nitrile rubber; ABS resins Acetonitrile is used as a chemical intermediate in pesticide manufacture. Solvent for both inorganic and organic compounds, including polymers. Starting material for many types of nitrogen-containing compounds, eg, amides, amines, higher molecular weight mono- and dinitriles; halogenated nitriles; ketones; isocyanates; and heterocycles, eg, pyridines and imidazolines A variety of lithium salts when dissolved in anhydrous organic solvents, eg, acetonitrile from electrolyte compositions for nonaqueous batteries.
Apparent Color COLORLESS, LIMPID LIQUID
Odor AROMATIC ODOR ; ETHER-LIKE ODOR
Boiling Point 81.6 DEG C AT 760 MM HG
Melting Point -45 DEG C
Molecular Weight 41.05
Density SP GR: 0.78745 @ 15 DEG C/4 DEG C
Odor Threshold Concentration Low: 70.0 mg/cu m; High: 70.0 mg/cu m; Irritating: 875 mg/cu m
Sensitivity Data Immediately irritating to the eye. May cause skin irritation. Vapor: irritating to eyes, nose and throat. Liquid: irritating to skin and eyes.
Environmental Impact Acetonitrile is released to the environment during its manufacture and use, from shale oil retorting and coal gasification, incineration of polyacrylonitrile, from automobile exhaust and cigarette smoke. If released to soil, aerobic biodegradation is likely to occur. Acetonitrile is expected to be mobile in soil and may evaporate from soil surfaces. Biodegradation is expected to be a major loss process in water. Acclimatization increases the biodegradation rate substantially. Volatilization may become competitive with other loss processes particularly at shallow water depths. Hydrolysis, photolysis, adsorption to suspended particles and sediments and bioconcentration in aquatic organisms are not likely to be important fate mechanisms. Acetonitrile is likely to be unreactive towards direct photolysis in air and the half-lives for its reaction with OH radicals and ozone have been estimated to be 535 days and 860 days, respectively. Therefore, it will persist in the troposphere for a long time and may be transported a long distance from its source of emission. Wet deposition may remove some of the atmospheric acetonitrile. Adequate data regarding its typical concentrations in air, water and total diet sample are not available to estimate intake from these exposure routes.
Environmental Fate TERRESTRIAL FATE: Although no conclusive study demonstrating the biodegradability of acetonitrile in grab soil samples is available, it can be inferred from the pure culture and biodegradability studies in water that the compound may biodegrade in soil. Photolysis studies in air(3,4) and hydrolysis studies in water suggest that acetonitrile would not undergo appreciable photolysis or hydrolysis in soil. Based on an estimated Koc value of 16(1,6), acetonitrile would be weakly sorbed to most soils. The high water solubility, moderately high vapor pressure , and weak soil sorption of the compound suggest that volatilization from soil surfaces and leaching into groundwater would be important. AQUATIC FATE: A number of biodegradation studies with sewage, activated sludge, and pure cultures serving as microbial organisms have shown that acetonitrile is biodegradable in water following acclimatization, as long as its original concentration is not too high (eg, 500 mg/l). The decomposition of the compound (concn 0.1 to 25 mg/l) in Ohio River water was 20% in 5 days and 40% in 12 days . Biodegradation was faster in water following acclimatization. Photochemical studies in the vapor phase(5,6) suggest that photodegradation in water may not be important. Hydrolysis is unimportant at the pH range normally present in natural waters . Based on the value of 2.93X10-5 atm cu m/mole for Henry's Law constant (H) and the relationship between H and volatility(6), volatilization of the compound from water may not be rapid, but may become competitive with other loss processes particularly at shallow water depths. The high water solubility and low Koc of acetonitrile would suggest that adsorption of the compound to suspended solids and sediment in water and bioconcentration in aquatic organisms would be unimportant. ATMOSPHERIC FATE: The rate constant for the reaction of acetonitrile with OH radicals in air has been determined to range from 1.9X10-14 to 4.94X10-14 cu cm/molecule-sec in the temperature range 20 to 27 deg C(1-5). Based on a rate constant of 3X10-14 cu cm/molecule-sec and the average daily OH radicals concn of 5X10 5 radicals/cu cm in the atmosphere , the half-life of this reaction is 535 days. The rate constant for the reaction of acetonitrile in air with ozone is 1.3X10-20 cu cm/molecule-sec(6). In a typical atmosphere where the average daily ozone concn is 7.2X10 11 molecules/cu cm , the half-life due to this reaction would be 860 days. The photochemical smog studies also show that this compound is unreactive towards photochemically-generated free radicals(8). Acetonitrile is also unreactive towards direct photolysis in the gas phase(7,9). EFFL: Acetonitrile was qualitatively detected in shale oil wastewaters and wastewater from coal gasification process(2,3).

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